Knife sharpening apparatus

ABSTRACT

A knife sharpening apparatus that has a grinding stone held in frictional engagement by semi-spherical metallic abutment members engaged in abutting relation to cylindrical shafts concentrically mounted on a threaded axle and supported in angle brackets by extending pin connections. Wing nut and bolt combinations hold the angle bracket in binding engagement to a horizontal bracket rigidly secured to a work area by a clamp and provide an expedient method for replacing a worn grinding stone.

United States Patent [191 Salvatore June 18, 1974 KNIFE SHARPENING APPARATUS Frank Salvatore, 2911 Breker St., Pittsburgh, Pa. 15212 Filed: Aug. 18, 1972 Appl. No.: 281,985

lnventor:

U.S. Cl. 51/210 Int. Cl. B24d 7/00, B24d 15/02 Field of Search 51/204, 210, 214

[56] References Cited UNITED STATES PATENTS 4/1914 Wallace 51/210 5/1949 Brockley 51/214 X 3/1954 Speare 51/210 3/1966 Thompson 51/210 X Primary Examiner-Donald G. Kelly Attorney, Agent, or Firm-Stanley J. Price, Jr.

[ ABSTRACT knife sharpening apparatus that has a grinding stone held in frictional engagement by semi-spherical metallic abutment members engaged in abutting relation to cylindrical shafts concentrically mounted on a threaded axle and supported in angle brackets by extending pin connections. Wing nut and bolt combinations hold the angle bracket in binding engagement to a horizontal bracket rigidly secured to a work area by a clamp and provide an expedient method for replacing a worn grinding stone.

5 Claims, 2 Drawing'Figures 1 KNIFE SI-IARPENING APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a knife sharpening apparatus and more particularly to a disc shaped grinding stone non-rotatably mounted on a threaded axle supported by brackets and easily removable from its bracket support when worn.

2. Description of the Prior Art The use of knife sharpening devices is known and disclosed in U.S. Pat. No. 2,232,402, which discloses a grinding wheel mounted on a shaft supported for rotation by a bracket with adjustments required to be made to the grinding wheel due to wearing of the grinding surface made by positioning the washers between the grinding wheel and guide member. In order to compensate for the wearing of the grinding wheel washers are added to the shaft as required to hold the grinding wheel in the desired position.

U.S. Pat. No. 1,342,275 discloses a machine for sharpening knives by reciprocating the knife blades between a pair of beveled grinding discs and rotating the discs relative to the knife. In addition, a pair of rotatable guides are disposed tangentially at opposite points within the V-groove formed by the beveled discs. The positioning of the rotatable guides in the V-groove of the beveled disc requires complete disassembly of the entire machine and removal of both discs in order to replace a worn grinding disc.

U.S. Pat. No. 2,673,426 discloses an abrasive rotatable wheel mounted on a hub supported by a pair of conical support members positioned opposite each face of the abrasive wheel. Each conical support member must be removed from the hub when a worn abrasive wheel is replaced.

U.S. Pat. No. 3,229,426 discloses a device for sharpening blades comprising a rotatable abrading element engaged to the leg of an angle frame by a bolt and a wing nut combination. The knife is sharpened by moving the abrading tool back and forth across the face of the cutting edge of a knife held rigid in a vice.

Several problems are encountered with conventional knife sharpening apparatus. The grinding stone is mounted on a shaft or spindle by means requiring considerable effort in removing when worn grinding stones are to be replaced for new ones. In addition, the burdensome task of removing the old stone results in considerable loss of production time.

The conventional knife sharpener provides a rotatable grinding stone or wheel mounted on a shaft. As a result, the drawing of the knife edge across the rotating surface of the stone reduces the operators control of the knife edge against the stone causing the edge to be dulled rather than sharpened.

SUMMARY OF THE INVENTION The hereinafter described invention comprises a disc shaped grinding stone with a central bore through which is passed an externally threaded axle. Each face of the grinding stone abuts a semi-spherical metallic abutment member with the semi-spherical end portion of the member non-rotatably positioning the grinding stone on the axle. The flat end portion of each abutment member is frictionally engaged to the end portion of a cylindrical shaft concentrically mounted on the externally threaded axle by means of internally threaded bores in the end portion of each shaft.

The mating of the externally threaded axle in the internally threaded bore of the cylindrical shafts exerts frictional forces on the flat end portions of each semispherical metallic abutment member. The cylindrical shafts are supported by angle brackets and are connected to the brackets by extending pins passing through aligned bores of the bracket and shaft. The angle brackets are, in turn, supported on horizontal brackets by cap screws means and wing nut and bolt combinations. The wing nut and bolt combinations provide a quick method of disassembling the apparatus for replacement of a worn grinding stone. The entire apparatus is secured to any work area by a clamp screw means.

This invention provides a non-rotatable disc shaped grinding stone mounted on a threaded axle held rigid by frictional forces generated against the stone by semispherical abutment members abutting each face of the stone and cylindrical shafts screwed on to the threaded axle and in turn frictionally pressed against the flat end portion of the abutment members. Consequently, when a knife edge is drawn across the stone surface the stone does not rotate permitting the operator to maintain maximum control of the knife edge and obtain the degree of sharpening desired.

Additionally, by supporting the threaded axle in angle brackets by a pin connection and rigidly retaining the angle bracket in position by wing nut and bolt com binations, the angle bracket can easily be removed permitting expedient replacement of worn grinding stones on the threaded axle.

Accordingly, a feature of this invention is to provide an expedient means by which a worn grinding stone of a knife sharpener can be replaced with a new grinding stone. Rather than disassembling the entire combination only the angle bracket secured to the horizontal bracket by the wing nut and bolt combinations need be removed. By releasing the pin connection between the angle bracket and cylindrical shaft, the shaft can be removed from threaded engagement with the threaded axle. Once the shaft is removed the frictional forces applied to the grinding stone through the semi-spherical abutment member are released and both the grinding stone and the semi-spherical abutment member are freed from their connection and easily removed from the end of the threaded axle.

Another feature of this invention is to provide a means for rigidly mounting a grinding stone for sharpening knives and cutting tools. The disc shaped grinding stone of this invention is non-rotatably held in place by frictional forces applied to each face of the stone by the arcuate end portion of the abutting members. The semi-spherical abutment members are, in turn, constrained from rotating by frictional forces generated at the flat end portion of the members by the cylindrical shafts rigidly supported on the threaded axle by the mating combination of external threads of the axle and internal threads in the bore of the cylindrical shaft. The described frictional forces are transmitted to each of the members coaxially aligned on the threaded axle by rotation of the cylindrical shaft which is supported by the angle bracket rigidly secured to the horizontal bracket by the wing nut and bolt combinations.

The invention is illustrated and described in the accompanying drawings in which:

FIG. 1 is a perspective view of the knife sharpener in which is illustrated the disc shaped grinding stone nonrotatably positioned by the cylindrical shafts and semispherical abutment members supported by bracket means.

FIG. 2 is a view in side elevation taken along the line Illl of FIG. 1, showing the concentric alignment of the disc shaped grinding stone, semi-spherical abutment member and cylindrical shafts non-rotatably mounted on the threaded axle. Also is shown the horizontal bracket means for supporting the combination and the clamp means for securing the invention to a work surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings and in particular to FIG. 2 there is illustrated the knife sharpening apparatus generally designated by the numeral comprising a cylindrical shaft 12 having at one end a bore 14 extending through the center of the shaft 12 and to the midpoint of the shaft 12. The bore 14 of shaft 12 is internally threaded and mates with the external threads of threaded axle 16. The semi-spherical abutment member 18 comprises a flat end portion 20 which abuts the end portion 22 of cylindrical shaft 12. Arcuate end portion 24 of semi-spherical abutment member 18 abuts the face 25 of disc shaped grinding stone 26.

Rubber bushing 28 fits within bore 30 of semispherical abutment member 18 through which passes threaded axle 16. Disc shaped grinding stone 26 is supported on threaded axle 16 by the rubber bushing 32 seated within the center of bore 34 of grinding stone 26.

The second semi-spherical abutment member 36 comprises arcuate end portion 38 which abuts the face 27 of disc shaped grinding stone 26 and flat end portion 40 which abuts the end portion 42 of the second cylindrical shaft 44. Rubber bushing 46 Seats within bore 48 of semi-spherical abutment member 36 through which passes threaded axle 16. The second cylindrical shaft 44 having at end portion 42 a bore 50 extending through the center of the shaft 44 and to approximately the midpoint of the shaft 44. The bore 50 of shaft 44 is internally threaded and mates with the external threads of threaded axle 16.

Shafts 12 and 44 are positioned in spaced relation ship on threaded axle 16. When the dimension between the end portions 22 and 42 of shafts l2 and 44 respectively are reduced by threadedly securing the shaft 44 to threaded axle l6, shaft 12 exerts a frictional force on the planar end portion 20 of semi-spherical abutment member 18. Semi-spherical abutment member 18 in turn exerts a frictional force on the face 25 of grinding stone 26. The face 27 of grinding stone 26 is then further urged against the arcuate end portion 38 of the second semi-spherical abutment member 36 to be moved into frictional engagement. Because of the reduction in the dimension between the ends of the cylindrical shafts l2 and 44 the planar end portion 40 of semi-spherical abutment member 36 abuts the end portion 42 of shaft 44 to maintain the described frictional forces.

Angle brackets 51 and 52 support cylindrical shafts 12 and 44 by connecting pins 54 and 56 extending through aligned boxes in angle bracket 51 and cylinder shaft 12 and angle bracket 52 and cylindrical shaft 44.

Angle brackets 51 and 52 are rigidly secured to horizontal bracket 54. Angle bracket 51 is held in binding engagement to horizontal bracket 54 by cap screws 57. Angle bracket 52 is held in binding engagement to horizontal bracket 54 by combinations wing nuts 58 and bolts 60. The horizontal end portion of angle bracket 51 abuts the horizontal end portion of angle bracket 52 on the surface of horizontal bracket 54 maintaining each angle bracket securely in position on horizontal bracket 54 during operation of the knife sharpening apparatus.

The wing nuts 58 and bolts 60 combinations are provided for easy assembly and disassembly of the knife sharpener 10. Once wing nuts 58 and bolts 60 are released from their threaded engagement angle bracket 52 is removed from its connection to cylindrical shaft 44 by disconnecting the pin 56 extended through the aligned bores of shaft 44 and angle bracket 52. Then by rotating handle 45 on cylindrical shaft 44 counterclockwise cylindrical shaft 44 is freed from the frictional engagement with semi-spherical abutment member 36, thereby allowing grinding stone 26 to be removed from threaded axle 16. This feature of the invention alleviates the task of a complete dismantling of the apparatus when a grinding stone is to be replaced.

Finally, the clamp screw 60 on horizontal bracket 54 secures rigidly the rollaway knife sharpener 10 to a stationary work area such as a table or bench.

According to the provisions of the patent statutes, l have explained the principle, preferred construction and mode of operation of my invention and what is now considered to represent its best embodiment has been illustrated and described. However, it should be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

l. A knife sharpening apparatus comprising,

a first cylindrical shaft having an internally threaded bore,

an axle threaded externally along the entire length thereof,.

an end portion of said threaded axle threadedly secured in said threaded bore of said first cylindrical shaft,

a first abutment member having a planar end portion and an arcuate other end portion,

said first abutment member having an axial bore therethrough,

said first abutment member mounted on said axle with said planar end portion frictionally engaging said first cylindrical shaft end portion,

a disc shaped grinding stone with a central bore therethrough,

said axle extending through said grinding stone central bore with one face of said grinding stone arranged in abutting relation with said first abutment member arcuate end portion,

a second abutment member mounted on said axle and having a planar end portion and an arcuate other end portion,

6 said arcuate end portion of said second abutment ranged to receive said first and second cylindrical member positioned in abutting relation with the shaft pin members, respectively. opposite face of said grinding stone, 3. A knife sharpening apparatus as set forth in claim a second cylindrical shaft with an internally threaded 2 which includes,

bore arranged to threadedly receive the other end 5 a horizontal support bracket positioned in spaced reportion of said axle, and lation relative to said grinding stone, and said second abutment member planar end portion cap screw means for rigidly securing said first angle positioned to frictionally engage said second cylinbracket to said horizontal support bracket. drical shaft end portion to thereby maintain said 4. A knife sharpening apparatus as set forth in claim grinding stone non-rotatably mounted on said 10 3 which includes, threaded axle. wing nut and bolt means for retaining said second 2. A knife sharpening apparatus as set forth in claim angle bracket in binding engagement with said horl which includes, izontal support bracket.

first and second spaced angle brackets with aligned 5. A knife sharpening apparatus as set forth in claim bores therethrough, 4 which includes, said first and second cylindrical shafts having outclamp screw means for rigidly securing said horizonwardly extending pin members, tal support bracket to a work area. said first and second spaced angle bracket bores ar- 

1. A knife sharpening apparatus comprising, a first cylindrical shaft having an internally threaded bore, an axle threaded externally along the entire length thereof, an end portion of said threaded axle threadedly secured in said threaded bore of said first cylindrical shaft, a first abutment member having a planar end portion and an arcuate other end portion, said first abutment member having an axial bore therethrough, said first abutment member mounted on said axle with said planar end portion frictionally engaging said first cylindrical shaft end portion, a disc shaped grinding stone with a central bore therethrough, said axle extending through said grinding stone central bore with one face of said grinding stone arranged in abutting relation with said first abutment member arcuate end portion, a second abutment member mounted on said axle and having a planar end portion and an arcuate other end portion, said arcuate end portion of said second abutment member positioned in abutting relation with the opposite face of said grinding stone, a second cylindrical shaft with an internally threaded bore arranged to threadedly receive the other end portion of said axle, and said second abutment member planar end portion positioned to frictionally engage said second cylindrical shaft end portion to thereby maintain said grinding stone non-rotatably mounted on said threaded axle.
 2. A knife sharpening apparatus as set forth in claim 1 which includes, first and second spaced angle brackets with aligned bores therethrough, said first and second cylindrical shafts having outwardly extending pin members, said first and second spaced angle bracket bores arranged to receive said first and second cylindrical shaft pin members, respectively.
 3. A knife sharpening apparatus as set forth in claim 2 which includes, a horizontal support bracket positioned in spaced relation relative to said grinding stone, and cap screw means for rigidly securing said first angle bracket to said horizontal support bracket.
 4. A knife sharpening apparatus as set forth in claim 3 which includes, wing nut and bolt means for retaining said second angle bracket in binding engagement with said horizontal support bracket.
 5. A knife sharpening apparatus as set forth in claim 4 which includes, clamp screw means for rigidly securing said horizontal support bracket to a work area. 